1109-15-5Relevant articles and documents
The solid-state structure of bis(pentafluorophenyl)zinc
Sun, Yimin,Piers, Warren E.,Parvez, Masood
, p. 513 - 517 (1998)
Using the published method of Wiedenbruch, bis(pentafluorophenyl)zinc, 1, was prepared from anhydrous ZnCl2 and 2 equiv. of LiC6F5 in diethyl ether. Base-free 1 was obtained in 60-65% yield by repeated distillation of the initially formed bis(diethyl) ether adduct of 1. The X-ray quality crystals of 1 were obtained from benzene solution. The molecular structure of 1 revealed a near linear geometry for the two-coordinate zinc center (C(1)-Zn-C(7) = 172.6(2)°), typical of monomeric ZnR2 derivatives. In the crystal structure, stacking interactions between C6F5 rings on adjacent molecules is a dominant motif, with ring centroid to ring centroid distances of 3.503 and 3.563 A observed. A weak intermolecular C-F...Zn interaction between F(2) and an adjacent zinc center, as judged by the close contact of 2.849(2) A, also appears to be an important aspect of the crystal structure. Compound 1 is an effective but nonselective C6F5 transfer agent to BCl3; 1: monoclinic, space group P21/n, a = 11.902(2) A, b = 7.732(2) A, c = 13.735(2) A, β = 110.58(1)°, V = 1183.4(4) A3, Z = 4, R = 0.048, Rw = 0.069.
σ- versus π-activation of alkynyl benzoates using B(C6F5)3
B?hr, Alexander,Wilkins, Lewis C.,Ollegott, Kevin,Kariuki, Benson M.,Melen, Rebecca L.
, p. 4530 - 4547 (2015)
We have prepared a range of alkynyl benzoates in high yields and have investigated their reactivities with the strong Lewis acid B(C6F5)3. In such molecules both σ-activation of the carbonyl and π-activation of the alkyne are possible. In contrast to the reactivity of propargyl esters with B(C6F5)3 which proceed via 1,2-addition of the ester and B(C6F5)3 across the alkyne, the inclusion of an additional CH2 spacer switches off the intramolecular cyclization and selective σ-activation of the carbonyl group is observed through adduct formation. This change in reactivity appears due to the instability of the species which would be formed through B(C6F5)3 activation of the alkyne.
Synthesis and photophysical properties of imine borane adducts towards vapochromic materials
Soltani, Yashar,Adams, Samuel J.,B?rger, Jennifer,Wilkins, Lewis C.,Newman, Paul D.,Pope, Simon J.A.,Melen, Rebecca L.
, p. 12656 - 12660 (2018)
A series of alkynyl aryl conjugated aldehydes and imines were prepared and their adducts with various Lewis acidic boranes have been studied via NMR, absorption, and luminescence spectroscopies in solution. The imine-B(C6F5)3 adduct showed remarkable solution stability, and was then trialled in vapochromism experiments using simple impregnated paper strips to examine the fluorescence responses.
Silica-Grafted Borato Cocatalysts for Olefin Polymerization Modeled by Silsesquioxane Borato Complexes
Duchateau, Robbert,Van Santen, Rutger A.,Yap
, p. 809 - 816 (2000)
The syntheses and reactivity studies of silsesquioxane-borato complexes are described. Treatment of B(C6F5)3 with (c-C5H9)7Si8O12(OH) and (c-C5H9)7Si7O9(OH) 3 in the presence of a Br?nsted base yields the silsesquioxane-borates X+{[(c-C5H9)7Si8O 13]B(C6F5)3}- (1a, X+ = PhN(H)Me2+; 1b, X+ = Et3NH+) and X+{[(c-C5H9)7Si7(OH) 2O10]B(C6F5)3} - (1b, X+ = PhN-(H)Me2+; 2b, X+ = Et3NH+), respectively. When the more nucleophilic base pyridine is used, (C6F5)3B·NC5H5 (3) is formed instead, demonstrating the competition between B(C6F5)3 and H+ to react with the amine. The dimethylaniline in 1a and 2a is readily exchanged by NEt3 to form 1b and 2b. With the nucleophilic Lewis base NC5H5, the B-O bond in 1a and 2a is split, yielding (C6F5)3B·NC5H5 (3) and the free silsesquioxanes. Complexes 1 and 2 rapidly undergo hydrolysis under formation of the hydroxyl complexes X+{(C6F5)3BOH}- (4a, X+ = PhN(H)Me2+; 4b, X+ = Et3NH+). Likewise, alcoholysis of 1a and 2a with i-PrOH yields the alkoxide {PhN(H)Me2}+{i-PrOB(C6F5) 3}- (5). The B-O bond is only moderately stable toward early-transition-metal alkyls. Nevertheless, Cp2Zr(CH2Ph)2 + 1a and Zr(CH2Ph)4 + 2a form single-site ethylene polymerization catalysts. Detailed reactivity studies demonstrated that both B-O and B-C bond splitting plays a crucial role, as not 1a and 2a, but their decomposition product B(C6F5)3 is the actual cocatalyst. The solid-state structures of 1a and 4b were determined by single-crystal X-ray analysis.
Borane Adducts of Hydrazoic Acid and Organic Azides: Intermediates for the Formation of Aminoboranes
Bl?sing, Kevin,Bresien, Jonas,Labbow, René,Michalik, Dirk,Schulz, Axel,Thomas, Max,Villinger, Alexander
, p. 6540 - 6544 (2019)
The reaction of HN3 with the strong Lewis acid B(C6F5)3 led to the formation of a very labile HN3?B(C6F5)3 adduct, which decomposed to an aminoborane, H(C6F5)NB(C6F5)2, above ?20 °C with release of molecular nitrogen and simultaneous migration of a C6F5 group from boron to the nitrogen atom. The intermediary formation of azide–borane adducts with B(C6F5)3 was also demonstrated for a series of organic azides, RN3 (R=Me3Si, Ph, 3,5-(CF3)2C6H3), which also underwent Staudinger-like decomposition along with C6F5 group migration. In accord with experiment, computations revealed rather small barriers towards nitrogen release for these highly labile azide adducts for all organic substituents except R=Me3Si (m.p. 120 °C, Tdec=189 °C). Hydrolysis of the aminoboranes provided C6F5-substituted amines, HN(R)(C6F5), in good yields.
Interaction of titanium(III) zwitterionic complex Cp[η 5-C5H4B(C6F5) 3]Ti with organic halides: Synthesis and X-ray crystal structure determination of zwitterionic titanocene monohalides
Strunkina,Minacheva,Lyssenko,Burlakov,Baumann,Arndt,Strunin,Shur
, p. 557 - 565 (2006)
The reaction of the titanium(III) zwitterionic complex Cp[η 5-C5H4B(C6F5) 3]Ti (1) with CCl4 at 20 °C under Ar results in the formation of hexachloroethane and the zwitterionic titanocene monochloride Cp[η5-C5H4B(C6F 5)3]TiCl (3) containing a B(C6F 5)3 moiety in the η5-cyclopentadienyl ring. Under similar conditions, the reaction of 1 with 1,2-dibromoethane affords ethylene and the corresponding zwitterionic monobromide Cp[η 5-C5H4B(C6F5) 3]TiBr (4). An X-ray diffraction study of 3 and 4 revealed the presence of a coordinative bond between the ortho-fluorine atom of one of the C6F5 substituents and the positively charged titanium centre. In the interaction of 1 with n-propyl iodide at 20 °C, titanocene diiodide, B(C6F5)3 and propylene are produced. The mechanism of this interesting reaction is discussed. The synthesized zwitterions 3 and 4 are able to catalyze the ring-opening polymerization of ε-caprolactone in a toluene solution and in bulk. The highest activity in this process is exhibited by 3. The first X-ray diffraction study of Cp 2TiI2 has been carried out.
Exploiting single-electron transfer in Lewis pairs for catalytic bond-forming reactions
Aramaki, Yoshitaka,Hotta, Mao,Imaizumi, Naoki,Kumagai, Jun,Ooi, Takashi
, p. 4305 - 4311 (2020)
A single-electron transfer (SET) between tris(pentafluorophenyl)borane (B(C6F5)3) andN,N-dialkylanilines is reported, which is operativeviathe formation of an electron donor-acceptor (EDA) complex involving π-orbital interactions as a key intermediate under dark conditions or visible-light irradiation depending on the structure of the aniline derivatives. This inherent SET in the Lewis pairs initiates the generation of the corresponding α-aminoalkyl radicals and their additions to electron-deficient olefins, revealing the ability of B(C6F5)3to act as an effective one-electron redox catalyst.
Methane activation by a borenium complex
Liu, Yizhen,Dong, Weishi,Li, Zhen Hua,Wang, Huadong
, p. 1843 - 1851 (2021)
The selective functionalization of methane under ambient conditions remains a formidable challenge for chemists. While most studies have focused on transition metal complexes, much less attention has been devoted to molecular complexes based on non-metal elements, despite them being more sustainable and less environmentally impactful. Here, we report that an N-heterocyclic carbene-stabilized borenium complex can activate methane under relatively mild conditions. The resulting methylborenium complex can readily transfer the methyl group to catecholborane (HBcat), which can lead to a synthetic cycle for the conversion of methane to MeBcat. Both experimental and theoretical mechanistic studies suggest that the C–H bonds of methane are activated via a σ-bond metathesis pathway. Such direct aliphatic C–H borylation can be extended to other alkanes, such as ethane and octane. The formed alkylborenium complexes can react with terminal alkynes via 1,2-alkylboration to install both the alkyl and boryl functionalities onto organic scaffolds.
A Dimer of Hydrogen Cyanide Stabilized by a Lewis Acid
Bl?sing, Kevin,Bresien, Jonas,Labbow, René,Schulz, Axel,Villinger, Alexander
, p. 9170 - 9175 (2018)
A highly labile dimer of hydrogen cyanide, HCN???HCN, was extracted from liquid HCN by adduct formation with the bulky Lewis acid B(C6F5)3, affording HCN???HCN?B(C6F5)3, which was fully characterized. The influence of the solvent (HCN, CH2Cl2, and aromatic hydrocarbons) on the crystallization process was studied, revealing dimer formation when using HCN or CH2Cl2 as solvent, whereas aromatic hydrocarbons led to the formation of monomeric arene??HCN?B(C6F5)3 adducts, additionally stabilized by η6-coordination of the aromatic ring system similar to well-known half-sandwich complexes.
1,3-Carboboration of iodonium ylides
Gazis, Theodore A.,Mohajeri Thaker, Bayan A. J.,Willcox, Darren,Ould, Darren M. C.,Wenz, Jan,Rawson, Jeremy M.,Hill, Michael S.,Wirth, Thomas,Melen, Rebecca L.
, p. 3345 - 3348 (2020)
Herein, we disclose the utilisation of iodonium ylides to access a range of boron dienolates. Heating of acyclic iodonium ylides in the presence of different aryl boranes leads to the formation of rare 1,3-carboboration products. This methodology could not be expanded to cyclic iodonium ylides which instead formed a Lewis acid-base adduct. Products proved to be remarkably stable under a wide range of conditions allowing for their long term storage.
